The invention relates to a dental implant for insertion into a jawbone and for fastening a tooth replacement.
A great many dental implants are known, of which the implant known from DE 10 2006 053 260 A1 will serve as an example, which implant, like most other known implants, is provided with a thread on its conical outer surface. With this thread, which is often self-tapping, the implant is screwed with force into a hole formed in the jawbone, where it remains for some time in order to become incorporated, until such time as it can be established that the process of incorporation has been successfully completed.
Most implant failures occur in the critical early phase of incorporation between the second and fourth weeks. At this stage there is a break in terms of stability, caused by a decline of the primary stability and by the increase in secondary stability started by the process of incorporation.
In the known implants, it is regarded as imperative to achieve a high degree of primary stability. This is to be understood as meaning that the implant, after insertion, is connected as firmly as possible to the bone. This is permitted, on the one hand, by the implant having the greatest possible contact with the bone, and, on the other hand, by the bone that surrounds the implant being as firm as possible. This is based on the idea that a high degree of primary stability also promises at a later stage a higher degree of secondary stability, and on the idea too that the implant can be subjected as soon as possible to loads.
The measures proposed for this purpose in terms of macrostructure entail either a compaction of the bone prior to insertion of the implant, for example by a bone expansion screw and/or by the use of a screw implant, in which case the bone is also compacted by the thread among other things.
The known screw implants have the disadvantage that a compaction of the bone represents bone compression, that is to say crushing. This appears to ignore the fact that the forces acting on the implant cause iatrogenic damage, which necessarily lengthens the healing time, because the crushed spongy substance and the compact substance first have to be degraded and then built up again. The crushing of the bone also increases the risk of a gap generally forming around the implant, which also fails to withstand a rotational load.
After the period of incorporation is completed, the implant has to be exposed in a further intervention. For this purpose, the mucosa across the implant is cut open under local anesthesia and a gingiva shaper (a small titanium coping) is screwed onto the implant. This gingiva shaper then protrudes through the mucosa which, over the following weeks, attaches itself to the gingiva shaper and heals. After about one to two weeks the gingiva shaper is temporarily replaced by a special impression coping specifically adapted to the implant, which impression coping is designed to permit an absolutely exact impression of the implant for the production of the tooth replacement. After the impression has been taken, the gingiva shaper is again fastened on the implant to ensure that the shape of the gum does not change. When the tooth replacement is ready, the gingiva shaper is unscrewed again from the implant and replaced by an abutment (titanium post), which remains permanently in the mouth for the purpose of fastening the tooth replacement.
This known method has the disadvantage that, after the period of incorporation, the mucosa across the implant has to be cut open in order to apply a gingiva shaper there, and this requires further local anesthesia and a further healing time for the new wound.
A further disadvantage is the use of an impression coping which, in exchange for the gingiva shaper, has to be screwed onto the implant for taking the impression and which, after the impression has been taken, is replaced again by the gingiva shaper in order to ensure that the shape of the gingiva does not change during the waiting period before the final tooth replacement is finished.